Goal Seek or Solver to Solve for two Unknows?

[CWEngineer]

Hi,

I am trying to figure out if Goal Seek or Solver would be the most appropriate to find two values (Qd for LRB & Qd for NR) that when they are multiplied by a desired value (8 and 24,respectively) would give me another desired value (665.1). Please see attach excel spreadsheet for what I am trying to do.

(8)(Qd for LRB) + (24)(Qd for NR) = 665.1

Really appreciate your help in your guidance on how to accomplish this.

Thanks

 

[Denial]

I'm almost certainly missing something here, but it looks like all you are trying to do is solve a single equation for two unknowns.[ ] If so, there is an infinity of possible answers.[ ] You need to introduce another equation, converting the problem to two equations for two unknowns.[ ] Or you need to introduce some sort of optimisation requirement, such as that you require the sum of (Qd for LRB) and (Qd for NR) to be a minimum.

Or you need to explain your requirements in a bit more depth.

 

[IDS]

You need at least one more constraint. At the moment there are an infinite number of equally valid solutions.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[zelgar]

As the others posted, you have an infinite number of results. Actually, the formula you've posted results in a line:
Qd for NR = (665.1 - 8(Qd for LRB))/24
This result in a line with Qd for NR ranging from 0 to 27.7125 and Qd for LRB ranging from 83.1375 to 0 (if we're only looking at the cases where both Qd's aren't negative).